1 files changed, 64 insertions, 0 deletions

diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
index 83259b873333..5f833f7adba1 100644
--- a/arch/arm/include/asm/tls.h
+++ b/arch/arm/include/asm/tls.h
@@ -1,6 +1,9 @@
 #ifndef __ASMARM_TLS_H
 #define __ASMARM_TLS_H
 
+#include <linux/compiler.h>
+#include <asm/thread_info.h>
+
 #ifdef __ASSEMBLY__
 #include <asm/asm-offsets.h>
         .macro switch_tls_none, base, tp, tpuser, tmp1, tmp2
@@ -50,6 +53,49 @@
 #endif
 
 #ifndef __ASSEMBLY__
+
+static inline void set_tls(unsigned long val)
+{
+        struct thread_info *thread;
+
+        thread = current_thread_info();
+
+        thread->tp_value[0] = val;
+
+        /*
+         * This code runs with preemption enabled and therefore must
+         * be reentrant with respect to switch_tls.
+         *
+         * We need to ensure ordering between the shadow state and the
+         * hardware state, so that we don't corrupt the hardware state
+         * with a stale shadow state during context switch.
+         *
+         * If we're preempted here, switch_tls will load TPIDRURO from
+         * thread_info upon resuming execution and the following mcr
+         * is merely redundant.
+         */
+        barrier();
+
+        if (!tls_emu) {
+                if (has_tls_reg) {
+                        asm("mcr p15, 0, %0, c13, c0, 3"
+                            : : "r" (val));
+                } else {
+#ifdef CONFIG_KUSER_HELPERS
+                        /*
+                         * User space must never try to access this
+                         * directly.  Expect your app to break
+                         * eventually if you do so.  The user helper
+                         * at 0xffff0fe0 must be used instead.  (see
+                         * entry-armv.S for details)
+                         */
+                        *((unsigned int *)0xffff0ff0) = val;
+#endif
+                }
+
+        }
+}
+
 static inline unsigned long get_tpuser(void)
 {
         unsigned long reg = 0;
@@ -59,5 +105,23 @@ static inline unsigned long get_tpuser(void)
 
         return reg;
 }
+
+static inline void set_tpuser(unsigned long val)
+{
+        /* Since TPIDRURW is fully context-switched (unlike TPIDRURO),
+         * we need not update thread_info.
+         */
+        if (has_tls_reg && !tls_emu) {
+                asm("mcr p15, 0, %0, c13, c0, 2"
+                    : : "r" (val));
+        }
+}
+
+static inline void flush_tls(void)
+{
+        set_tls(0);
+        set_tpuser(0);
+}
+
 #endif
 #endif  /* __ASMARM_TLS_H */